1. Field of the Invention
The present invention pertains to cellular communication systems and, more specifically, to providing the location of a mobile station in a cellular communication system.
2. Description of the Prior Art
Nowadays the use of wireless communication devices like for example mobile phones or personal digital assistants (PDA) is widespread. With the emergence of new technologies the use of these devices is not limited to voice applications.
Of the new types of services that is expected to be broadly accepted in the near future are services providing enhanced functionality to the end user of a mobile device based on the location of the user of the mobile device, so called Location Based Services (LBS). Services that can be provided if the location of the device is known are e.g., directing the user of the device to a specific destination, providing the local weather forecast or providing information with regard to the nearest relevant shop or point of interest.
Depending on the type of service to be provided different methods of determining the location of a device can be applied. Some services require a very accurate location; other services like the local weather forecast can function with a less accurate location. Well-known methods of determining the location of a device are based on the location of the base station of the radio cell the mobile device is connected to. The location of the base station is of course known to the operator of the network to which those base stations belong. Those methods of determining the location of the mobile device based on the location of the base station the device is connected to, function correctly as long as the mobile device is connected to its home network. The identity of the relevant base station is known from the standard signaling traffic in the network and the location, for instance expressed in x-y coordinates, can be retrieved from a database and provided to the service provider as the location of the mobile device. However, as soon as the mobile device is connected to a base station of another network, the problem arises that based on the Cell-ID (which is always disclosed to the home network of the subscriber, to enable the mobile device to function in the visited network) the location of the relevant base station can only be derived based on the Cell-ID if the location information of all base stations of the visited is available to the operator of the home network. For a variety of reasons operators are reluctant to disclose the exact location of their network's base stations. Another problem is the maintenance of the database; base stations might be added to the networks. Therefore location-provisioning methods based on the location of the base station do not provide interoperability between different network providers. Therefore there is a need for a method of providing the location of a mobile device without publicly disclosing the location of all the base stations of a network.
The prior art fails to disclose a method and system for providing the location of a mobile station based on Cell-ID in a secure and simple manner between different networks.